Monday, 14 May 2012

T 153/11 – Not Quite The Same

The criteria for assessing lack of novelty are quite restrictive under the EPC as interpreted by the case law – which is something even Examining Divisions (ED) sometimes forget.

Claim 1 before the Board read:
An apparatus for controlling supercharging pressure in an internal combustion engine, wherein the engine includes:
an exhaust passage (20);
a turbine (32) located in the exhaust passage (20), the turbine (32) having variable position vanes (36) which open and close to change the flow rate of an exhaust gas through the turbine, wherein the exhaust gas applies a driving torque to the turbine (32);
an intake passage (22);
a compressor (34) located in the intake passage (22), the compressor (34) supplying air to the internal combustion engine depending on the driving torque of the turbine (32);
a recirculating passage (24) connecting the exhaust passage (20) and the intake passage (22) to each other to recirculate exhaust gas from the exhaust passage (20) to the intake passage (22); and
an EGR control valve (50) located in the recirculating passage (24), wherein the position of the EGR control valve (50) is varied to adjust the quantity of exhaust gas passing through the recirculating passage (24);
wherein the position of the variable vanes (36) is controlled according to the position of the EGR control valve (50) by setting a limit value (Va) for the position of the variable vanes (36) when the vanes are being closed to limit the operational range of the variable vanes (36) depending on the degree of opening of the EGR control valve (50), thereby preventing an excessive amount of exhaust gas from flowing into the recirculating passage (24).
The ED found this claim to lack novelty over document D1.

The Board did not agree:

[4.1] The decision under appeal argues lack of novelty over D1. This document, see figure 1, relates to the same type of variable displacement turbocharger with valve controlled exhaust gas recirculation as the application.

Here the variable displacement turbo-charger is controlled in response to corrections in the EGR rate of the EGR control system, see abstract and figure 8, between blocks 103 and 106.

In more detail, see figures 6 and 7, vane control signal LADUTY is determined according to different schemes (either following step S45 in figure 6, or one of steps S50, S51 in figure 7) for different engine operating states.

It is always derived from a duty signal DUTB2, which depends on EGR valve position via control and corrections signals MEGRM, KEGR1, VNEGR2, see figure 5, but has different offsets or none depending on operation state. Figure 6, step S45, shows a downward correction by DUTDT for heavy acceleration, where the turbocharger tends to run too fast, to effectively open up the vanes and so slow the turbine down, column 19, lines 12 to 16, reducing boost pressure in the intake, column 7, lines 47 to 49, and thus back-pressure in the exhaust passage.

This effect is similar to that in the present application, see above, and is achieved by the valve position dependency of the vane control signal LADUTY. In that they produce the same or similar effect and both involve valve position dependency the two approaches can be said to be “comparable”, as argued in the decision under appeal.

[4.2] However, it is not enough that functions or effects are “comparable”, the same or similar to demonstrate lack of novelty. Rather, the prior art must also achieve these functions and effects in the same way as the claimed invention, and, applying the generally accepted standard for assessing novelty, this must be derivable clearly and unambiguously from D1. That is not the case in the present appeal.

In D1 the vane control signal LADUTY depends on the EGR valve position as well as on other variables. Vane position thus varies with EGR valve position among others across some range. The limits of that range and how they might correlate with the EGR valve position are entirely unknown, let alone that it can assumed conclusively and with certainty that the limit value in the direction of opening depends on the EGR valve position. This indeed need not be so. Nor can the correction of LADUTY by an offset be regarded in any way as a limitation in this particular sense, namely that of the limit value required by claim 1. This particular feature of the valve control, which represents the “core” or “essence” of the claimed invention is thus not clearly and unambiguously disclosed in D1. The subject-matter of claim 1 of the main request is thus novel over D1.

[4.3] The above feature is also not directly and unambiguously derivable from any of the other prior art cited in the search report. Briefly, in prior right document EP-A-1 031 719 the turbo vane signal Aturbr is based on the EGR valve opening value Aevr, see figures 15,20 and 21 and paragraphs [0149] and [0111]. A similar approach is taken in JP-A-2000002120. In US-A-6 076 353 vane and valve position control signals are each calculated from intake pressure and mass airflow, while in JP-A-2000170580 the two are controlled so that the supercharge pressure and fresh air intake increase or decrease together. There is no mention in these documents, explicitly or otherwise, of limiting the operation range of the vane depending on the opening degree of valve.

4.4 The Board can but conclude that the apparatus of claim 1 is novel over the prior art as required by A 52(1) in combination with A 54.

The Board then remitted the case to the ED for further prosecution.

To download the whole decision, click here.

The file wrapper can be found here.